Dairy farmers had another slow month in December, delivering 40m litres less milk during the month than they did in 2004.

Once adjusted for butterfat, which has been on the rise since the summer, milk output came in 20m litres below quota, according to the Charles Holt/ Farmers Weekly profile.

Gross output reached 1.096bn litres, with a butterfat content of 4.15%.

Charles Holt of the Farm Consultancy Group said: “Butterfat in December was the strongest it has been since 1996.

“That’s because the silage has plenty of fibre but not a lot of energy, so cows aren’t milking as they ought.

Farmers should be buying concentrates to raise milk output, he added. “Quota is irrelevant this year.”

Quota prices have fallen back on the week, with very little leasing trade done and some sales of clean quota at around 4.8p/litre.